Dosing pumps for water treatment networks
Dosing pumps inject a very specific amount of chemical into a liquid stream. Besides wastewater networks, there are many other applications for dosing pumps. These include industrial, food processing, pulp and paper as well as boiler feed water treatment. In each case, the chemical being added has a specific process function and it is important to add the right amount of chemical to prevent operational problems.
Dosing pumps form part of the chemical dosing systems supplied by OdourPro. Find out more about our dosing systems our dosing systems here.
Dosing pumps and wastewater networks
There are two components of municipal wastewater systems collection / transportation networks and treatment plants:
Collection and transportation networks are made up of gravity pipelines, pump stations, andrising mains. It's common for wastewater conveyed in the networks to become septic, and as a result, emit hydrogen sulphide gas. This causes odour nuisance and corrosion of wastewater infrastructure.
An effective strategy for treating the septicity in wastewater networks is the implementation of chemical dosing. There are a number of dosing reagents used for septicity control, the most common and effective being ferrous chloride, calcium nitrate and magnesium hydroxide.
There are many variable factors to take into account when implementing wastewater network chemical dosing.It is important to choose the most suitable reagent for the particular application and the correct size and type of dosing pump.
Types of dosing pumps
Both Diaphragm and Peristaltic dosing pumps are commonly used at wastewater pump stations.
Diaphragm pumps work on a reciprocating principle similar to a piston. When the diaphragm flexes in one direction, it increases the chamber volume drawing chemical into the chamber. When it flexes in the opposite direction it compresses the chemical out of the chamber. Non-return valves on the supply and discharge side ensure that there is no reverse flow from the discharge side.
Peristaltic pumps use a different method of operation completely. The dosing chemical enters a flexible tube from which it is squeezed into the process stream. The tube usually forms a U-shape and there are two or more rollers pinching the tube at different points. As one roller moves along the tube, it pushes dosing chemical out the discharge port and creates space behind it for the next dose of chemical to enter the tube. Each cycle, an identical volume of dosing chemical is injected into the process stream.
Selecting a dosing pump
Diaphragm pumps are suitable for handling a wide range of chemicals. In terms of wastewater applications, they are used for ferrous chloride and calcium nitrate dosing. Pump models must be selected based on discharge pressure rating as well as dosing volume.
Peristaltic pumps are used for magnesium hydroxide dosing in wastewater networks. Magnesium hydroxide has a tendency to block injection systems, and peristaltic pumps are more resistant to this than diaphragm pumps. Also, magnesium hydroxide is typically dosed into wet wells rather than rising mains so there is no need for the high pressure capabilities of diaphragm pumps.
Optimising dosing pumps
The first step in optimising a dosing pump is selecting the correct size pump for your application. When a pump is sized correctly, it operates in its optimum range providing consistency in performance and long-term reliability.
OdourPro chemical dosing systems come with PLCs for controlling the chemical dosing performance. Dosing rates can be set up on a variable basis to adjust according to the wastewater flow or as a constant doing rate. The PLC can be configured with alarm settings to warn of any abnormal conditions.
Servicing dosing pumps
Chemical dosing is a critical part of wastewater network septicity control and a failure of the system could lead to an environmental incident and fines. It is therefore important to perform regular servicing and maintenance tasks. This includes the basic cleaning of filters and injection quills. It is also important to check the system for leaks or blockages.
OdourPro provides maintenance and servicing contracts to ensure your system is working optimally at all times. Our telemetry options give supervisors and maintenance professionals access to information about the system at all times so prompt action can be taken in the event of a fault.
OdourPro is a leading supplier of wastewater septicity control solutions for odour management. We have the expertise to help you analyse your wastewater network and put in place the right solution for your needs.
OdourPro on 21 November 2016
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